Implement Mojo SyncLoad

content/common/url_loader_factory.mojom

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module content.mojom;
 
 import "url_loader.mojom";
 
+[Native]
+struct URLSyncLoadResult;
+
 interface URLLoaderFactory {
   // Creats a URLLoader and starts loading with the given |request|. |client|'s
   // method will be called when certain events related to that loading
   // (e.g., response arrival) happen. |request_id| is for compatibility with
   // the existing Chrome IPC.
   CreateLoaderAndStart(URLLoader& loader,
                        int32 routing_id,
                        int32 request_id,
                        URLRequest request,
                        URLLoaderClient client);
-};
+
+  // Loads the resource for the given |request| synchronously.
+  // |request_id| is for compatibility with the existing Chrome IPC.
+  [Sync] SyncLoad(int32 request_id, URLRequest request)
+      => (URLSyncLoadResult result);
+};